High-brightness 300 W fiber laser at ~950 nm

Fiber lasers operating in the 900 nm wavelength band have garnered significant interest due to their extensive array of applications. However, their development is still hindered by various factors, with the output power currently being restricted to the hundred-watt level. Despite numerous proposed solutions, achieving higher power outputs in this wavelength band remains a challenge. In this Letter, we have pioneered a new approach that harnesses stimulated Raman scattering within a fiber nonlinear gain framework. We have engineered a high-brightness laser diode source by utilizing techniques such as spectral beam combining and polarization beam combining, which are then employed directly for pumping. Through meticulous optimization of the fiber laser system and by incorporating brightness enhancement strategies such as multimode fiber beam cleaning and resonant cavity spatial mode selection, we have achieved a record-breaking output power of 315 W with an outstanding beam quality factor of M² = 2.45 for high-brightness fiber lasers at ∼950 nm.